Seat belts are provided in vehicles to restrain occupants in the event of a sudden braking event or accident. In some markets, legislation requires that these are provided for each seating position of a vehicle intended for a vehicle occupant to occupy. Some larger vehicles have the internal space to house a third row of seats which, when provided, are generally disposed at or near the rear of the vehicle. Some vehicle designs are intended to provide the third row as an option, because without the third row, the vehicle can still carry around five occupants and have a much larger luggage space than is the case when the third row of seats is installed. However, larger families may require the third row and prefer to forego the extra luggage space.
Seat belt anchorages or anchors are often provided in or secured to the vehicle body shell. The location of the or each seat belt anchorage relative to the seating positions provided in the vehicle are typically dictated by legislation for a given market, and the location of each anchorage should be optimised to provide comfort for the seat belt user. Most seat belts are of the three-point variety, where two lower anchors are provided on the floor of the vehicle (or lower part of the seat) to secure a lap-belt, and a single shoulder anchor or upper anchorage is usually in a side pillar of the vehicle body, to secure a shoulder belt passing across the passenger's body from the opposite lower anchor. When connected to the vehicle body, the anchor can withstand the forces required of it. However, because they are in the vehicle body, where firstly detection of damage may be difficult and secondly repair or such damage may be difficult, anchor points on the bodywork also need to be able to withstand the effects of more minor loadings without deformation. As a standard, a loading approaching 1.5 tonnes is taken as a minimum force required to be absorbed by the anchorage when applied by the seat belt. Loading exceeding 1.5 tonnes applied to the seat belt anchorage via the seat belt is likely only to be occasioned in an accident that will result in significant damage to the vehicle. However, at loadings less than 1.5 tonnes (ECE REGULATION No. 14—SAFETY BELT ANCHORAGES etc) a vehicle may not be irreparably damaged and yet damage to a seat belt anchorage cannot be permitted for the reasons just given.
Seat belt anchorages in vehicle bodies generally involve a welded nut attached to a suitable body panel and into which a bolt can be fixed to secure a seat belt element, such as a D-loop, through which the belt is guided over the user's shoulder in use; a seat belt reel; or a fixed clasp for releasable connection of a buckle of the belt. Such a nut invariably requires some reinforcement to meet the requirements of ECE Regulation 14 (or equivalent standard). The degree of reinforcement depends to some extent on the direction of the potential loading. Steel, or aluminium, panels, out of which vehicle bodies tend to be made, have great strength when formed into box sections. They are capable of accepting substantial loads when these are applied in shear. However, when forces are applied orthogonally to the plane of a panel, deformation may result from lower loads. Even when panels are reinforced, the loading is usually such as to apply a peeling load on joints in the sections (assuming these are formed, as is generally the case, by interconnected panels). Reinforcement of a panel might be effected by having a local thickening of the panel where the reinforcement is required, for example by welding another layer of the panel material to the panel around the nut (in the case of interest). Generally, only one such layer can, as a practical matter, be applied to either side of a panel.
In the case of aluminium panels, welding is impractical as most suitable nuts are made from steel and so are unsuitable for welding to aluminium. Other means of reinforcement involve the use of fillets and braces. These are all satisfactory, but they tend to be installed in a vehicle body shell prior to completion of the Body-in-White (BIW) stage of manufacture. That is the eponymous stage of vehicle manufacture at which the vehicle body is complete as an assembly of panels and has the requisite environmental proactive coatings applied prior to final paint work application and assembly of vehicle components.
At this point in manufacture, at least in respect of vehicles that might have a third row, it is certainly unknown which of them will, or will not, have this option. Certainly, it is not desirable to provide yet a further stock-keeping unit for this. Consequently, it would normally be the case that all the reinforcements required of the bodyshell for an acceptable seat belt anchor will always be provided, for all the seats that might be installed, regardless of whether or not all the vehicles so produced will be destined to have the third row of seats and employ the reinforcement provided. Obviously, for those vehicles that do not end up with a third row, the provision of the reinforcement is unnecessary.
Large passenger vehicles such as sports utility vehicles (SUV) or multi-purpose vehicles (MPV), generally have four pillars on each side that connect the roof to rest of the vehicle bodywork. The A pillar is at the front and, on either side of the vehicle, it surrounds the front windscreen; the B pillar is between the front and rear doors, and acts as a door jamb for the front doors and hangs the rear doors; the C pillar is behind the rear doors and acts as the jamb for those doors; and the D pillar is in the rear corner of the vehicle and surrounds the rear windscreen which, usually in such vehicles, is in a tailgate. Of course, multiple different options exist and the aforementioned arrangement is merely typical of SUV and/or MPV type vehicles with which the present invention is mostly concerned. However, the arrangement is typical of many other vehicle types.
Because of the rear tailgate, the D pillar therefore also usually provides a mounting for a seal against which the tailgate closes. The pillars A to D are generally hollow box sections made by welding together two or more pressed metal panels. The shapes involved can be complex, but there is a limit to the extent which such panels can be pressed and shaped prior to welding. Generally D pillars are formed from three panels welded together, often in a somewhat triangular section in places. Indeed, it is often found that, at the point where it is desirable to provide an upper seat belt anchorage, the section of the D pillar may be quite close to a right-angle triangle where the first side, the hypotenuse, is formed by the external body panel, a second side forms part of the opening frame for the tailgate, and the third side completes the pillar section and faces towards the front of the vehicle.
It should incidentally be noted, that use of these geometric descriptions in this specification are extremely approximate and for illustration only, and do not represent the precise shape of the components being described.
Pillars should have as large a cross-sectional area as possible, to increase their strength and resistance to torsion and bending. Consequently, while it would in theory be possible to align the third panel in a more parallel relation with respect to the first panel, this would reduce the cross-sectional area of the pillar and undermine the fundamental purpose of the pillar. However, having the third panel face the front is disadvantageous for the reasons discussed above for connection of a seat belt. Significant reinforcement features may be required to resist panel deformation for a given the direction of force applied via the seat belt to a seat belt anchor connected to the third panel. The seat belt cannot be connected to the second face, because that is framing the tailgate and, for reasons explained below, is actually outside the vehicle. The first, hypotenuse panel cannot be employed, as it forms the external surface of the vehicle and its orientation with respect to the seat belt may not be appropriate.
It is an object of the present arrangement to provide a seat belt anchor that addresses the points mentioned above, or at least mitigates some of the effects of the aforementioned issues.